http://unstats.un.org/unsd/publication/SeriesM/SeriesM_58rev1e.pdf" >EU context : Derived by EMN from the UN Recommendations on Statistics of International Migration and OECD Glossary of Statistical Terms
1. At the international level, no universally accepted definition for migration exists.
2. The International Organization for Migration (IOM) defines migration as follows: 'movement of a person or a group of persons, either across an international border (international migration), or within a state (internal migration), encompassing any kind of movement of people, whatever its length, composition and causes'. This broad definition covers all forms of migration (voluntrary/forced migration, internal/international migration, long-term/short-term migration), different motives for migration (migration because of political persecution, conflicts, economic problems, environmental degradation or a combination of these reasons or migration in search of better economic conditions or conditions of survival or well-being, or other motives such as familiy reunfication) and irrespective of the means used to migrate (legal/irregular migration). Thus it includes migration of refugees, displaced persons, economic migrants and persons moving for other purposes, including family reunification.
3. Under the UN, the definition 'movements for shorter periods' would not be considered migration.